Injection cartridge



Aug. 5, 1969 D. E. WILLIAMSON INJECTION CARTRIDGE Filed Feb. 8, 1967 FIG.|

INVENTOR.

DONALD E. WILLIAMSON ATTORNEYS United States Patent 3,459,337 INJECTION CARTRIDGE Donald E. Williamson, Miami, Fla., assignor to Cordis Corporation, Miami, Fla., a corporation of Florida Filed Feb. 8, 1967, Ser. No. 615,020 Int. Cl. B67d 5/54; G01f 11/42, F04c N04 US. Cl. 222183 9 Claims ABSTRACT OF THE DISCLOSURE An apparatus for injecting liquids consists of a unitary combination of a pump and flexible sealed reservoir. The unit is entirely filled with fluid, thereby preventing air from being injected after the reservoir is empty. For the injection of parenteral liquids, the entire unit can be sterilized by the manufacturer.

This invention relates to injection apparatu and particularly to the injection of parenteral fluids useful in angiography and like fields.

Injection apparatus finds frequent application in the internal administration of medicine and test fluids to a patiet. Injection apparatus of the type commonly in use generally consists of a fluid reservoir, typically a syringe, which is attached to a driving means for forcing the fluid from the reservoir into a catheter for transporting the fluid to the patient. After the fluid has been expelled from the reservoir, the syringe must be refilled. This is both inconvenient and time consuming. In addition, froth or foam is often introduced into the syringe during the refilling process; this is probably due to the intake of fluids at high velocity through the relatively narrow inlet openings of the syringe. The tendency to froth or foam may be at least partly alleviated by refilling the syringe at a slower rate. However, this increases the time consumed by the employment of such apparatus and is undesirable.

The problems encountered with injection apparatus of this type may be alleviated by providing a disposable prefilled injection cartridge which may be used but once and thrown away. I have found that a superior cartridge may be provided by fitting a collapsible liquid container or reservoir integrally to the inlet port of a suitable pump such as a rotary pump having an outlet conduit adapted to accept standard fittings, e.g. a standard Luer fitting, of the type with which syringes and catheters are commonly equipped. The pump and container form a unitary disposable cartridge at the outside of which connections may be made to the drive shaft of the pump when attached to a driving source, such as an electric motor, which is used in conjunction with control apparatus to monitor and control such injection variables as the volume of fluid to be injected, the rate of injection, etc. In such an apparatus, the driving action of the pump causes a smooth flow of liquid to be delivered; the liquid will be free of any froth or foam due to cavitation or entrapped air.

The unit is entirely filled with fluid to the exclusion of air so that air cannot be injected when the fluid is used up. As fluid is injected the reservoir collapses and air never enters the system.

The pump may be any one of a number of well-known types of pumps, but is preferably a rotary pump of positive displacement so that it will also function as a metering device. The entire unit is conveniently made of plastic for reasons of economy and ease of fabrication. The various stationary parts of the assembly must be compatible as regards the method chosen for their attachment, such as heat sealing, etc. The materials for the rotating parts will be chosen with regard to their coeflicient of friction against themselves and the stationaryparts, as well as 3,459,337 Patented Aug. 5, 1969 the ability to fabricate them to the necessary dimension tolerances.

The reservoir is formed of a flexible, preferably transparent or translucent plastic, so that a visual indication of the amount of fluid remaining may be had. If the contents are to be sterile, the materials will be chosen in consideration of the type of sterilization used, i.e., electron beam, gas sterilization or autoclaving. Plastics such as polyethylene or other polyolefins may be used for the stationary parts and nylon or Teflon may be used for the rotating parts.

The entire unit, when filled, is provided with a membrane forming a seal at the drive shaft, which may be designed to be ruptured when an injection is made.

My invention will become more readily apparent when the foregoing generalities are taken in connection with the following detailed description of the drawings in which:

FIG. 1 is a side elevational view of one form of injection apparatus utilizing the injection cartridge of my invention.

FIG. 2 is a front elevational view along the lines 22 of FIG. 1 showing the injection cartridge in greater detail;

FIG. 3 is a side sectional view along the lines 3-3 of FIG. 2; and

FIG.4 is a side sectional view of a portion of the injection cartridge of FIG. 3 showing an alternative form of seal.

Referring now more particularly to FIG. 1, there is shown one form of injection apparatus utilizing the cartridge of my invention. A housing 10 mounted on a base plate 12 encloses an electric motor 14 having a shaft 16 extending through the housing. A control panel 18 having control knobs and switches 20 is mounted on the front of the housing, the control knobs and switches being electrically connected to the motor 14 by means of a cable harness 22. Also mounted on the base plate 12 is a frame 24 in which an injection cartridge 26 is slidably positioned. The base plate 12 is attached to a column 28 which is fixed to a wheeled platform 30 in order that the injection apparatus may readily be moved where necessary.

FIG. 2 is a front elevational view in section taken along the lines 22 of FIG. 1 and showing the injection cartridge of my invention in greater detail. The cartridge includes a pump housing 32 having an internal rotor 34 keyed to a shaft 35 and an external rotor 36 surrounding the rotor 34. The rotors 34 and 36 rotate on fixed centers, but the center of rotation of the rotor 36 is eccentrically located with respect to the center of rotation of the rotor 34. The housing 32, the shaft 35, and the gears 34 and 36 may advantageously be formed from a relatively inexpensive material such as nylon in order that the injection cartridge may be disposed of after a single usuage. An inlet port 38 is located in the upper portion of the pump housing 32; a similar outlet port 40 (shown in phantom) is located in the lower portion of the pump housing. The

. preferably transparent, material such as plastic. On the inside of the casing 46 is a transparent fluid container 48 which is fastened in fluid-tight fashion around the upper portion of the inlet port 38 by means of a band 50, or heat sealing. The container 48, which may advantageously be formed from a thin film of a plastic such as polyethylene heat sealed along the top edge after being filled with the injection fluid, is partially supported by a wedge 52 (FIG. 3) which maintains the fluid contents of the container above the level of the port 38 at all times in order that the container 52 may be completely emptied of fluid when desired.

As may be seen from FIG. 3, the outlet port 40 terminates in a shaped portion 54 of the pump housing to form an outlet conduit which is designed to accommodate a catheter or other injection fitting. The conduit 54 is covered by a removable cap 56 to prevent leakage and to protect the sterility of the contents of the assembly prior to use.

The injection fluid is supplied to the pump from the fluid container 48. Although several methods of filling the container may be utilized, one convenient method is to attach the container to the pump inlet port, fill the container with the fluid to be injected, and then seal the upper portion of the container by any convenient means, such as by heat sealing. During the filling process, the cap 56 may be removed from the conduit 54 of the pump housing 32 to allow a small portion of the fluid to drain from the pump, thus ensuring that the pump is completely filled with injection fluid and is free of entrapped air. It may also be desirable to rotate the pump slowly and briefly while filling. Other methods of filling the container and priming the pump may, of course, be used, and the above is but one method of doing this. After the container 48 is filled and sealed, the shaft seal 58 (or 66) is applied, the cap 56 is replaced on the conduit 54 and the entire cartridge, including the pump and the fluid container, is sterilized. As an alternative method, the pump and container assembly may be presterilized and evacuated, thereafter being filled through the pump by a presterilized fluid, the pump being rotated in reverse to accomplish filling.

An internal spline 56 is formed in the rear portion of the shaft 35; the shaft 16 of the motor 14 mates with this spline to provide a positive drive when the injection cartridge is fitted into the frame 24 as in FIG. 1. A circular membrane 58 preferably formed from a readily rupturable material such as a thin polyethylene film is sealed to the shaft 35 and the housing 32 to maintain the sterile environment of the interior of the pump. When the pump is actuated by the motor 14, the seal 58 is broken by the relative motion between the shaft 35 and the housing 32.

The operation of the injection cartridge of my invention may now be understood in detail. The pump shown in detail in FIGS. 2 and 3 of the drawing is a positive displacement rotary pump of the internal gear type. The inner rotor 34 of the pump is driven by the shaft 35 to which it is keyed for rotation, while the outer rotor 36, which rotates on a fixed center that is offset from the center of rotation of the rotor 34, is in turn driven by the rotor 34. When an injection is to be administered, the cartridge 26 is positioned in the frame 24 on the base plate 12 and the shaft 16 of the motor 14 is fitted snugly into the internal spline 56 of the pump shaft 35. The cap 56 is removed from the conduit 54 of the pump housing and a catheter or other injection fitting is snugly pressed over the conduit. The injection variables (volume, rate etc.) are then set on the control panel 18 and the motor 14 is actuated to begin the injection.

When the motor 14 is operated, it drives the pump shaft 35 which ruptures the seal 56 and sets the rotors 34 and 36 in motion. As the latter rotates, the chamber between the teeth of the inner and outer rotors gradually increases in size through approximately 180 of each revolution until the chamber reaches its maximum size which is equivalent in volume to the volume of the missing tooth on the inner rotor. During this half cycle, injection fluid flows from the fluid container 48 into the inlet port 38 and thence into the chamber formed between the inner and outer rotary gears. During the next half cycle of .4 operation, the filled chamber is carried toward the outlet port and gradually decreases in size until substantially all of the liquid contained in the chamber is exhausted through the port 40 and thence into the conduit 54.

As the fluid is withdrawn from the fluid container 48, the container adjusts its volume to the volume of the remaining fluid by increasingly deforming and collapsing under the influence of the atmospheric pressure of its environment; this prevents formation of a back pressure which would interfere with pumping etficiency and which would allow the possiblity of frothing or foaming of the injection fluid during pumping. Further, since the container 48 is completely enclosed and is tightly sealed to the pump housing 32, aif is prevented from entering the pump after container 48 is emptied of liquid, and being thereby injected in an undesirable manner. At the conclusion of the injection, the cartridge 26 is removed from the frame 24 and disposed of as a unit. A new cartridge is then inserted in the frame and a second injection is immediately ready for administration.

The ease and simplicit with which injections may be administered with the injection apparatus of my invention may now be appreciated. The injection cartridge, which is prefilled and presterilized, is quickly fitted to the external driving apparatus and is prepared for injection in a matter of seconds. Multiple injections of the same or different type of injection fluid are readily accommodated due to the ease with which the cartridge may be fitted to and removed from the driving apparatus. In addition, the simple mounting means which I provide allows the utilization of my cartridge in conjunction with different control apparatus so that maximum flexibility is obtained.

Various modifications may be made in the injection cartridge described herein without departing from the spirit and scope of my invention. For example, FIG. 4 is a side sectional view of a portion of the injection cartridge of FIG. 3 showing an alternative method of sealing the pump to preserve sterility of its contents during shipment and storage. The pump shaft 62 is provided with a collar 64, either integrally constructed or hermetically sealed to it. The seal is formed of a thin cylindrical plastic 68 which bridges the gap between the pump housing and the collar 64 and is heat sealed to both, thereby isolating the interior portions of the pump from the external environment. The seal 66 is readily broken when the shaft 62 is actuated by the driving motor.

From the above it may be seen that I have provided an improved injection apparatus which is particularly useful for the parenternal administration of injection fluids in angiography and the like fields. Further, I have provided a disposable injection cartridge which can be presterilized, which provides a constant visual check of the remaining fluid, and which provides a smooth flow of liquid without foaming or frothing. The provision of a completely filled system with a flexible reservoir completely eliminates the possibility of injecting entrained air at any time during use, or the uncontrolled injection of air when the reservoir is empty.

Although this invention has been described with reference to an apparatus for injecting parenteral fluids, other types of fluids can also be handled in this type of apparatus. It will also be apparent to those skilled in the art that various changes and modifications may be made in the apparatus described above without departing from the scope of my invention and it is intended that the foregoing be considered as illustrative only.

Having described and illustrated a preferred embodiment of my invention, I claim:

1. A disposable parenteral fluid injection cartridge for use with a drive unit which includes guide surfaces for holding the cartridge and a power source, said cartridge including a reservoir and a built-in pump mechanism assembled into a unitary package having mounting surfaces engageable with said guide surfaces, and comprising a housing for said pump mechanism, including an inlet conduit, an outlet conduit, and an exteriorly accessible drive means operatively associated with said mechanism and engageable with said power source when said package is held mounted on said drive unit, means mounting said reservoir on said housing and in communication with and sealed to said inlet conduit, said reservoir having flexible walls and containing sterile parenteral injection fluid which fills said reservoir and said pump mechanism and said conduit to the exclusion of gas in the entire cartridge, and means closing said outlet conduit.

2. The combination defined in claim 1 Wherein said pump is a rotary pump.

3. The combination defined in claim 2 wherein said pump is of positive displacement.

4. The combination defined in claim 1 wherein sealing means connects between the drive means and housing.

5. The combination defined in claim 1 wherein the reservoir is mounted on the top of the housing, and a rigid casing mounted on top of the housing surrounds and supports the reservoir.

6. The combination defined in claim 1 in which said pump housing includes a pair of dove-tailed portions on opposite sides thereof for rapidly mounting said injection apparatus on a frame having keyways corresponding to said dove-tail Portions.

7. A disposable injection cartridge as defined by claim 1 comprising a rotary positive displacement pump mechanism within said housing, said pump mechanism including an exteriorly accessible rotatable shaft for operatively associating with said mechanism, a membrane fastened to said housing and to said shaft forming a seal,

a flexible external sealed reservoir mounted on the top of said pump housing communicating with said inlet conduit, a rigid casing mounted on the top of said pump housing surrounding said reservoir.

8. The combination defined in claim 7 in which said pump housing includes a pair of dove-tailed portions on opposite sides thereof for rapidly mounting said injection apparatus on a frame having keyways corresponding to said dove-tail portions.

9. A disposable injection cartridge as defined by claim 1 wherein the drive means and power source are engageable by a linear motion and the guide surfaces and mounting surfaces are parallel to the direction of said motion, whereby the cartridge may be engaged with the drive unit through said motion.

References Cited UNITED STATES PATENTS 1,751,169 3/1930 Parker 221-197 X 2,517,321 8/1950 Jordan 222 X 3,027,846 4/1962 Schindler 103126 3,232,496 2/ 1966 Rockwell et a1 222383 SAMUEL F. COLEMAN, Primary Examiner H. S. LANE, Assistant Examiner US. Cl. X.R. 

